US2259990A

US2259990A - Valve

Info

Publication number: US2259990A
Application number: US320697A
Authority: US
Inventors: Baumann Karl
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1939-02-22
Filing date: 1940-02-24
Publication date: 1941-10-21
Anticipated expiration: 1958-10-21

Description

' ocr. 21, 1941. K, BAUMANN 2,259,990

VALVE Filed Feb. 24, 1940 H15 Attorney.

Patented Oct. 21, 1941 2,259,92'10 VALVE Y Karl Baumann, Wilmslow., England', assigner t0` General Electric Com New York pany, ancorporation of` Application February 24, 1940,'Se1"ial No. 320;(597

Y n In Great Britain February 22, 1939 (o1. 251-81) Y v 2 Claims.

This invention relates to steam or elastic fluid valves of what is known as the balanced doublebeat or double-seated type and has for its object to construct improved valves of this type in which the velocityy of steam through the valve fora given pressure drop is increased so that the dimensions of the valve for the passage of a given weight of steam per hour are reduced.

According to the invention in order to attain this object the channels by which the steam approaches and recedes from the valve seats are made respectively convergent and divergent whereby when the valve is open the velocity of the steam in its passage towards the valve seats gradually increases and on leaving the valve seats diminishes so that the steam attains substantially its maximum velocity as it passes over the valve seats. By this means the valve seat diameter for the passage of a given weight of steam per hour for the same pressure drop can be made less than would be the case with a double-beat valve of the ordinary type.

In double-beat valves of existing well known types the outer cylindrical portion of the valve is usually connected to the boss through which the valve spindle passes by means of radial ribs which together with the boss obstruct the passage of the steam.

In valves according to the present invention the boss may be arranged outside the steam pass and the ribs connecting the movable portion of the valve to the boss arranged at the largest diameter possible, the steam flowing across them in a radial direction. Thus a large area can be provided and the velocity of the steam can be kept low in a part where the direction of the ilow of steam changes. The ribs can conveniently be streamlined so as to reduce the pressure drop.

In such a construction the valve proper is free to expand symmetrically as a simple body and is not subject to distortions such as occur with the older type of valve.

In one construction the conical valve seats are ground so that the slant sides thereof will co1 verge to a common apex in the center line of the valvewhereby differential expansion which may occur in the valve seats and the valve itself does not aiect the proper seating of the valve on both seats.

The improved valve seats may be connected by means of a hollow cylindrical member'which locates the seats in the correct relative position. Said member is provided with small perforations A a strainer to prevent foreign matter passing through the gvalve. The seats may be either made in one'piece Vwth't-he cylindrical connecting portion so as to consist, for example, of a single casting, or the seats may be separatel parts secured in thefcorrect position atl the ends yof the cylindrical member. y

The single figure of the accompanying drawing is a vertical sectional View of a valve constructed in accordance with the invention.

I is a casing having an annular entry passage 2 and an exit passage'3 for the steam. In a cavity in the casing between the entry and exit passage is secured a shell 4 which carries an upper valve seat 5 and a lower valve seat 6. The valve spindle 'I is provided with a boss 8 which carries the movable part 9 of the valve by means of depending ribs I0. The ribs may be streamlined in the direction of the steam flow. The movable part 9 of the'valve which has a large central orice II surrounding the spindle is formed externally with upper and lower valve seats I2 and I3 to cooperate with the iixed valve seats 5 and B respectively. As shown in the drawing the annular channels indicated at I4 by which the steam approaches the Valve seats from the entry passage 2 are made convergent in the direction oi thesteam flow while those marked I5 by which the steam leaves the vvalve seats are madedivergent in the directionk of the steam flow so that the steam attains its maximum velocity as it passes over the valve seats. In the construction shown the valve seats are conical and ground so that the slant sides thereof, as indicated by the dashdotted lines a, b, will converge to a common apex c, in the axis of the spindle I. The fixed valve seats 5 and 6 are connected by a cylindrical member I6 forming part of the shell 4 which locates and maintains the seats 5 and 6 in their correct relative position. The member is provided with small perforations I1 to act as a strainer for the steam.

During operation elastic uid is admitted from a conduit to the annular passage 2. With the valve in the open position, as indicated, the fluid passes through the perforations I'I of the shell towards the outlet 3, one portion of the uid being conducted through the lower passages I4, I5 and another portion of the fluid through the upper passages I4,` I5 formed by the adjacent portions of the part 9 andthe valve seat 5. From the upper passage I5 the fluid flows radially inward through the spaces formed between adjacent depending ribs Irtowards the spindle `I through which the steam passes and thus acts as and .then downward through the space formed between the spindle and the inner, cylindrical surface of the part 9. With the elements arranged and formed as described above, the fluid reaches its maximum velocity near the seats 5 and 6, that is, the velocity of the iiuid increases until it reaches the seats 5 and then it decreases.

Valves of the improved construction are particularly suitable for use in turbine governing systems in which the valves are opened by oiloperated power pistons as the reduction of the out-of-balance force enables smaller operating gear to be employedand a greater sensitivity to be obtained, While the reduction obtainable in leakage with the valve closed is also important.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1..A double-seated valve comprising a casing having an inlet and an outlet, a shell seated in the casing and dening an annular channel therewith communicating with the inlet, the shell having a cylindrical perforated portion acting as a strainer for conducting uid from the channel to the outlet, other portions of the shell integral with and adjacent the opposite ends of the perforated portion forming valve seats and an end portion of the shell forming an opening communicating with the outlet, and a movable valve member in cooperative relation with the seats.

2. A double-seated valve comprising a casing having a detachable cover and forming an inlet and an outlet, a shell having a lower, an intermediate and an upper portion disposed Within the casing, the lower portion engaging a seat formed by the casing and the upper portion being engaged by the cover and thereby retained in position, the shell with the casing forming an annular channel communicating with the inlet, the intermediate portion of the shell being perforated to act as a strainer for conducting fluid from the channel to the outlet, the lower and upper portions of the shell having concentric inward projections dening two axially spaced valve seats concentrically located within the strainer, and a cylinder type movable valve member Within the shell in cooperative relation with the seats.

KARL BAUMANN.